From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-16.5 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id BFAA3C07E99 for ; Fri, 9 Jul 2021 09:00:36 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A554F613D9 for ; Fri, 9 Jul 2021 09:00:36 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231751AbhGIJDS (ORCPT ); Fri, 9 Jul 2021 05:03:18 -0400 Received: from mail.kernel.org ([198.145.29.99]:52928 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231494AbhGIJDR (ORCPT ); Fri, 9 Jul 2021 05:03:17 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id CA77A613D0; Fri, 9 Jul 2021 09:00:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1625821234; bh=VJ16V2VpdcasUBiXG5p6TX1Xjj34GA6UfKAZNthInl4=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=c3+1IFqJGIjEd4gUNkskhJH+38PycJK/HOnY83UZWpNB29PFUAxCmI/lzxEsA3rIW 2W+UX8Q4SqNmdC4y4UPMuZlldtD4xr72BMwn+7t6GpF8vxksW8JQSU51sjQbxBnagh ZSOEuXyGpFlZthPklSvx4SUCzYz/BMgYW6rCC22LW9JtMm1XEIL6UIy+RX3SljlbNa BsKbgGCnxDNTm30+Rzse4LUW6gE9Vm/PwixpxKxMcC+IOfIwbMFalhMtXKhNxDstoh xYh/LsBlaH6Vx5nx5vlEhbiaoBpEF3clBRc7a4O9kxx94/EdUQDLHoGDaB90JZvcEF tpJobRFVm/ojQ== Date: Fri, 9 Jul 2021 18:00:31 +0900 From: Masami Hiramatsu To: Shaobo Huang Cc: , , , , , , , , , , , , Subject: Re: [PATCH 4.4.y] arm: kprobes: Allow to handle reentered kprobe on single-stepping Message-Id: <20210709180031.adc7260b54645b0292a6f02a@kernel.org> In-Reply-To: <20210709024630.22268-1-huangshaobo6@huawei.com> References: <20210709024630.22268-1-huangshaobo6@huawei.com> X-Mailer: Sylpheed 3.7.0 (GTK+ 2.24.32; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Shaobo, Thanks for backporting! Greg, it seems this patch can be applied to 4.9 too without any issue. Thank you, On Fri, 9 Jul 2021 10:46:30 +0800 Shaobo Huang wrote: > From: Masami Hiramatsu > > commit f3fbd7ec62dec1528fb8044034e2885f2b257941 upstream > > This is arm port of commit 6a5022a56ac3 ("kprobes/x86: Allow to > handle reentered kprobe on single-stepping") > > Since the FIQ handlers can interrupt in the single stepping > (or preparing the single stepping, do_debug etc.), we should > consider a kprobe is hit in the NMI handler. Even in that > case, the kprobe is allowed to be reentered as same as the > kprobes hit in kprobe handlers > (KPROBE_HIT_ACTIVE or KPROBE_HIT_SSDONE). > > The real issue will happen when a kprobe hit while another > reentered kprobe is processing (KPROBE_REENTER), because > we already consumed a saved-area for the previous kprobe. > > Signed-off-by: Masami Hiramatsu > Signed-off-by: Jon Medhurst > Fixes: 24ba613c9d6c ("ARM kprobes: core code") > Cc: stable@vger.kernel.org #v2.6.25~v4.11 > Signed-off-by: huangshaobo > --- > arch/arm/probes/kprobes/core.c | 6 ++++++ > 1 file changed, 6 insertions(+) > > diff --git a/arch/arm/probes/kprobes/core.c b/arch/arm/probes/kprobes/core.c > index 3eb018fa1a1f..c3362ddd6c4c 100644 > --- a/arch/arm/probes/kprobes/core.c > +++ b/arch/arm/probes/kprobes/core.c > @@ -270,6 +270,7 @@ void __kprobes kprobe_handler(struct pt_regs *regs) > switch (kcb->kprobe_status) { > case KPROBE_HIT_ACTIVE: > case KPROBE_HIT_SSDONE: > + case KPROBE_HIT_SS: > /* A pre- or post-handler probe got us here. */ > kprobes_inc_nmissed_count(p); > save_previous_kprobe(kcb); > @@ -278,6 +279,11 @@ void __kprobes kprobe_handler(struct pt_regs *regs) > singlestep(p, regs, kcb); > restore_previous_kprobe(kcb); > break; > + case KPROBE_REENTER: > + /* A nested probe was hit in FIQ, it is a BUG */ > + pr_warn("Unrecoverable kprobe detected at %p.\n", > + p->addr); > + /* fall through */ > default: > /* impossible cases */ > BUG(); > -- > 2.12.3 > -- Masami Hiramatsu